DE 697 24 995 T2 discloses a device according to the class in the form of an electrical power supply system that has a portable power socket unit with a power socket and a secondary coil connected to this power socket. To be able to supply electrical energy to the portable unit via the secondary coil, a base unit is fixed in position, submerged in a drainage shaft in the roadway. The base unit has a primary coil for the inductive transfer of electrical energy to the secondary coil of the portable power socket unit and also electronics supplying the primary coil with electrical energy. The primary coil and the electronics are held in a housing that is sealed against the penetration of water. The electronics are connected to the power supply grid via a grid supply line that is fed through a bushing provided in the housing. To prevent the penetration of water into the inner space of the housing through the bushing, the bushing has a special seal.
The power socket unit described above has the disadvantage that the seal of the bushing is a possible leakage point if, for example, the seal becomes damaged due to vibrations or small animals under the ground. The sealing effect of the seal can also degrade after a certain amount of time; for example, the sealing material can become porous over time, so that this also poses the risk of allowing water penetration. To prevent this as much as possible, the seal must be inspected regularly, which is possible only with great effort. To do this, the cover of the housing must be removed and then the heavy coil and the sensitive electronics must be removed. Only then is the bushing sufficiently exposed that its leak-tightness can be tested. If the seal has become leaky, the ground above the seal must be excavated to allow the seal to be replaced from the outside of the housing.
In the area of inductive energy transfer to movable loads, for example, electric vehicles such as automobiles or trucks, there is the problem that the area around the submerged primary coil is often exposed to vibrations due to vehicles regularly driving over the ground, and this also applies a load on the seal.
GB 2477080 A discloses a rail track for track vehicles with a prefabricated track module in which the cable of a primary coil is laid between two running rails, extending in the longitudinal direction of the running rails. Laterally next to the running rails there are electrical or electronic components arranged in a box section. A passage hole runs out from the box section into the area between the rails, wherein lines for connecting the cable to the electrical or electronic components lead through the passage hole. Because the ground between the running rails is above the ground of the box section, and the electrical or electronic components are arranged on the ground of the box section, water penetrating into the box section or the area between the running rails collects in the lower-lying box section. To protect the electrical or electronic components from water, these components must be sealed in an appropriate watertight manner. These are connected with relatively great effort, because the lines going out from the components must have special seals.